1. Field of the Invention
This invention relates to an optoisolator leadframe assembly, more particularly to an optoisolator leadframe assembly including two aligned single pieces of emitter and receiver leadframe parts, each of which includes a rail and a plurality of leadframe units.
2. Description of the Related Art
U.S. Pat. No. 4,633,582 discloses a conventional optoisolator leadframe assembly (see FIG. 1) that is made from a single piece of a stamped metal sheet 9 including first and second rails 91, 92 that are coplanar, and emitter and receiver leadframe units 93, 94 extending between the first and second rails 91, 92 and including emitter and receiver leadframes 901, 902, respectively. Each of the emitter and receiver leadframes 901, 902 has a die-mounting pad 903 (904) for receiving one of a light emitting chip and a light detector (not shown), and a plurality of leads 905 (906). The die-mounting pad 903 of each of the emitter leadframes 901 is aligned with the die-mounting pad 904 of a corresponding one of the receiver leadframes 902. The aforesaid conventional optoisolator leadframe assembly is disadvantageous in that an additional apparatus is required to conduct twisting action of the emitter leadframe unit 93 so as to permit alignment of the die-mounting pads 903, 904 of an adjacent pair of the emitter and receiver leadframes 901, 902.
Taiwanese Laid Open publication No. 200743201 discloses another conventional optoisolator leadframe assembly (see FIG. 2) that includes first and second rails 81, 82 that are coplanar, a plurality of emitter leadframe units 83 extending between the first and second rails 81, 82, and a plurality of receiver leadframe units 84 disposed alternately with the emitter leadframe units 83. Each of the emitter and receiver leadframe units 83, 84 has a die-mounting pad 801 (802) and a pair of leads 803 (804). The first and second rails 81, 82 and the emitter leadframe units 83 are a single piece of a stamped metal sheet. Each of the receiver leadframe units 84 is cut and removed from the single piece of the stamped metal sheet, and is then reversed and repositioned accurately between an adjacent pair of the emitter leadframe units 83, which requires an additional apparatus to conduct the reversing and repositioning actions, which, in turn, results in an increase in the manufacturing costs.